2013-07-16 20:21:33 -04:00
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#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership.
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# The ASF licenses this file to You under the Apache License, Version 2.0
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# (the "License"); you may not use this file except in compliance with
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# the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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2014-08-16 19:59:34 -04:00
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import os
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2015-04-16 19:20:57 -04:00
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import sys
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2014-11-24 20:17:03 -05:00
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import gc
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from tempfile import NamedTemporaryFile
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2014-08-16 19:59:34 -04:00
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2015-04-16 19:20:57 -04:00
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if sys.version < '3':
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import cPickle as pickle
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else:
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import pickle
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unicode = str
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2014-09-03 14:49:45 -04:00
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__all__ = ['Broadcast']
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2012-10-19 13:24:49 -04:00
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# Holds broadcasted data received from Java, keyed by its id.
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2012-08-25 16:59:01 -04:00
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_broadcastRegistry = {}
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2012-10-19 13:24:49 -04:00
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def _from_id(bid):
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2012-08-25 16:59:01 -04:00
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from pyspark.broadcast import _broadcastRegistry
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2012-10-19 13:24:49 -04:00
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if bid not in _broadcastRegistry:
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raise Exception("Broadcast variable '%s' not loaded!" % bid)
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return _broadcastRegistry[bid]
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2012-08-25 16:59:01 -04:00
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class Broadcast(object):
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2013-12-29 20:15:07 -05:00
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"""
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A broadcast variable created with L{SparkContext.broadcast()}.
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Access its value through C{.value}.
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Examples:
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>>> from pyspark.context import SparkContext
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>>> sc = SparkContext('local', 'test')
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>>> b = sc.broadcast([1, 2, 3, 4, 5])
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>>> b.value
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[1, 2, 3, 4, 5]
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>>> sc.parallelize([0, 0]).flatMap(lambda x: b.value).collect()
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[1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
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>>> b.unpersist()
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>>> large_broadcast = sc.broadcast(range(10000))
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"""
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def __init__(self, sc=None, value=None, pickle_registry=None, path=None):
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"""
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Should not be called directly by users -- use L{SparkContext.broadcast()}
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instead.
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"""
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if sc is not None:
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f = NamedTemporaryFile(delete=False, dir=sc._temp_dir)
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self._path = self.dump(value, f)
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self._jbroadcast = sc._jvm.PythonRDD.readBroadcastFromFile(sc._jsc, self._path)
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self._pickle_registry = pickle_registry
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else:
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self._jbroadcast = None
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self._path = path
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def dump(self, value, f):
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pickle.dump(value, f, 2)
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f.close()
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return f.name
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def load(self, path):
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with open(path, 'rb', 1 << 20) as f:
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# pickle.load() may create lots of objects, disable GC
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# temporary for better performance
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gc.disable()
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try:
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return pickle.load(f)
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finally:
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gc.enable()
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2014-08-16 19:59:34 -04:00
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2014-09-03 14:49:45 -04:00
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@property
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def value(self):
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""" Return the broadcasted value
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"""
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if not hasattr(self, "_value") and self._path is not None:
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self._value = self.load(self._path)
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return self._value
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def unpersist(self, blocking=False):
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"""
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Delete cached copies of this broadcast on the executors.
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"""
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if self._jbroadcast is None:
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raise Exception("Broadcast can only be unpersisted in driver")
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self._jbroadcast.unpersist(blocking)
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os.unlink(self._path)
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def __reduce__(self):
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if self._jbroadcast is None:
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raise Exception("Broadcast can only be serialized in driver")
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self._pickle_registry.add(self)
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return _from_id, (self._jbroadcast.id(),)
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2014-08-16 19:59:34 -04:00
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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